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Viruses May 2023Base pairing based on hydrogen bonding has, since its inception, been crucial in the antiviral activity of arabinosyladenine, 2'-deoxyuridines (i.e., IDU, TFT, BVDU),...
Base pairing based on hydrogen bonding has, since its inception, been crucial in the antiviral activity of arabinosyladenine, 2'-deoxyuridines (i.e., IDU, TFT, BVDU), acyclic nucleoside analogues (i.e., acyclovir) and nucleoside reverse transcriptase inhibitors (NRTIs). Base pairing based on hydrogen bonding also plays a key role in the mechanism of action of various acyclic nucleoside phosphonates (ANPs) such as adefovir, tenofovir, cidofovir and O-DAPYs, thus explaining their activity against a wide array of DNA viruses (human hepatitis B virus (HBV), human immunodeficiency (HIV) and human herpes viruses (i.e., human cytomegalovirus)). Hydrogen bonding (base pairing) also seems to be involved in the inhibitory activity of Cf1743 (and its prodrug FV-100) against varicella-zoster virus (VZV) and in the activity of sofosbuvir against hepatitis C virus and that of remdesivir against SARS-CoV-2 (COVID-19). Hydrogen bonding (base pairing) may also explain the broad-spectrum antiviral effects of ribavirin and favipiravir. This may lead to lethal mutagenesis (error catastrophe), as has been demonstrated with molnutegravir in its activity against SARS-CoV-2.
Topics: Humans; Antiviral Agents; Nucleosides; Base Pairing; Hydrogen Bonding; COVID-19; SARS-CoV-2; Viruses
PubMed: 37243232
DOI: 10.3390/v15051145 -
The Journal of Infectious Diseases Nov 2023Herpes simplex virus 1 can cause severe infections in individuals who are immunocompromised. In these patients, emergence of drug resistance mutations causes...
BACKGROUND
Herpes simplex virus 1 can cause severe infections in individuals who are immunocompromised. In these patients, emergence of drug resistance mutations causes difficulties in infection management.
METHODS
Seventeen herpes simplex virus 1 isolates were obtained from orofacial/anogenital lesions in a patient with leaky severe combined immunodeficiency over 7 years, before and after stem cell transplantation. Spatial/temporal evolution of drug resistance was characterized genotypically-with Sanger and next-generation sequencing of viral thymidine kinase (TK) and DNA polymerase (DP)-and phenotypically. CRISPR/Cas9 was used to introduce the novel DP Q727R mutation, and dual infection-competition assays were performed to assess viral fitness.
RESULTS
Isolates had identical genetic backgrounds, suggesting that orofacial/anogenital infections derived from the same virus lineage. Eleven isolates proved heterogeneous TK virus populations by next-generation sequencing, undetectable by Sanger sequencing. Thirteen isolates were acyclovir resistant due to TK mutations, and the Q727R isolate additionally exhibited foscarnet/adefovir resistance. Recombinant Q727R mutant virus showed multidrug resistance and increased fitness under antiviral pressure.
CONCLUSIONS
Long-term follow-up of a patient with severe combined immunodeficiency revealed virus evolution and frequent reactivation of wild-type and TK mutant strains, mostly as heterogeneous populations. The DP Q727R resistance phenotype was confirmed with CRISPR/Cas9, a useful tool to validate novel drug resistance mutations.
Topics: Humans; Antiviral Agents; Herpesvirus 1, Human; Herpes Simplex; Severe Combined Immunodeficiency; Gene Editing; Drug Resistance, Viral; Acyclovir; Mutation; DNA-Directed DNA Polymerase; Immunologic Deficiency Syndromes; Drug Resistance, Multiple; Thymidine Kinase
PubMed: 37224525
DOI: 10.1093/infdis/jiad184 -
Biomedicines Apr 2023Monkeypox disease (Mpox) has threatened humankind worldwide since mid-2022. The Mpox virus (MpoxV) is an example of Orthopoxviruses (OPVs), which share similar genomic... (Review)
Review
Monkeypox disease (Mpox) has threatened humankind worldwide since mid-2022. The Mpox virus (MpoxV) is an example of Orthopoxviruses (OPVs), which share similar genomic structures. A few treatments and vaccines are available for Mpox. OPV-specific VP37 protein (VP37P) is a target for developing drugs against Mpox and other OPV-induced infections such as smallpox. This review spotlights the existing and prospective VP37P inhibitors (VP37PIs) for Mpox. The non-patent literature was collected from PubMed, and the patent literature was gathered from free patent databases. Very little work has been carried out on developing VP37PIs. One VP37PI (tecovirimat) has already been approved in Europe to treat Mpox, while another drug, NIOCH-14, is under clinical trial. Developing tecovirimat/NIOCH-14-based combination therapies with clinically used drugs demonstrating activity against Mpox or other OPV infections (mitoxantrone, ofloxacin, enrofloxacin, novobiocin, cidofovir, brincidofovir, idoxuridine, trifluridine, vidarabine, fialuridine, adefovir, imatinib, and rifampicin), immunity boosters (vitamin C, zinc, thymoquinone, quercetin, ginseng, etc.), and vaccines may appear a promising strategy to fight against Mpox and other OPV infections. Drug repurposing is also a good approach for identifying clinically useful VP37PIs. The dearth in the discovery process of VP37PIs makes it an interesting area for further research. The development of the tecovirimat/NIOCH-14-based hybrid molecules with certain chemotherapeutic agents looks fruitful and can be explored to obtain new VP37PI. It would be interesting and challenging to develop an ideal VP37PI concerning its specificity, safety, and efficacy.
PubMed: 37189724
DOI: 10.3390/biomedicines11041106 -
European Journal of Pharmaceutical... Jul 2023Cocktails of transporter probe drugs are used in vivo to assess transporter activity and respective drug-drug interactions. An inhibitory effect of components on...
PURPOSE
Cocktails of transporter probe drugs are used in vivo to assess transporter activity and respective drug-drug interactions. An inhibitory effect of components on transporter activities should be ruled out. Here, for a clinically tested cocktail consisting of adefovir, digoxin, metformin, sitagliptin, and pitavastatin, inhibition of major transporters by individual probe substrates was investigated in vitro.
METHODS
Transporter transfected HEK293 cells were used in all evaluations. Cell-based assays were applied for uptake by human organic cation transporters 1/2 (hOCT1/2), organic anion transporters 1/3 (hOAT1/3), multidrug and toxin extrusion proteins 1/2K (hMATE1/2K), and organic anion transporter polypeptide 1B1/3 (hOATP1B1/3). For P-glycoprotein (hMDR1) a cell-based efflux assay was used whereas an inside-out vesicle-based assay was used for the bile salt export pump (hBSEP). All assays used standard substrates and established inhibitors (as positive controls). Inhibition experiments using clinically achievable concentrations of potential perpetrators at the relevant transporter expression site were carried out initially. If there was a significant effect, the inhibition potency (K) was studied in detail.
RESULTS
In the inhibition tests, only sitagliptin had an effect and reduced hOCT1- and hOCT2- mediated metformin uptake and hMATE2K mediated MPP uptake by more than 70%, 80%, and 30%, respectively. The ratios of unbound C (observed clinically) to K of sitagliptin were low with 0.009, 0.03, and 0.001 for hOCT1, hOCT2, and hMATE2K, respectively.
CONCLUSION
The inhibition of hOCT2 in vitro by sitagliptin is in agreement with the borderline inhibition of renal metformin elimination observed clinically, supporting a dose reduction of sitagliptin in the cocktail.
Topics: Humans; Organic Cation Transport Proteins; HEK293 Cells; Biological Transport; Sitagliptin Phosphate; Metformin; Organic Cation Transporter 2; Drug Interactions
PubMed: 37142000
DOI: 10.1016/j.ejps.2023.106459 -
Frontiers in Cellular and Infection... 2023Liver inflammation is the main risk factor for developing liver fibrosis, cirrhosis, and even hepatocellular carcinoma in chronic hepatitis B (CHB) patients. To replace...
BACKGROUNDS & AIMS
Liver inflammation is the main risk factor for developing liver fibrosis, cirrhosis, and even hepatocellular carcinoma in chronic hepatitis B (CHB) patients. To replace biopsy, additional non-invasive biomarkers to diagnose and grade liver necroinflammation are urgently required in clinical practice.
METHOD
Ninety-four CHB patients, including 74 HBeAg-positive and 20 HBeAg-negative patients, were enrolled and started entecavir or adefovir therapy. Serum HBV RNA, HBV DNA, HBsAg, hepatitis B core-related antigen (HBcrAg), ALT and AST levels, as well as intrahepatic HBV DNA and cccDNA were measured at baseline and during treatment. Liver inflammation was assessed at baseline and month 60 by liver biopsy. Inflammation regression was defined as a ≥1-grade decrease according to the Scheuer scoring system.
RESULTS
In HBeAg-positive CHB patients, at baseline, serum HBsAg and HBcrAg levels negatively correlated with inflammation grade, while ALT and AST levels positively correlated with inflammation grade. AST plus HBsAg exhibited excellent diagnostic ability for significant inflammation with an AUROC of 0.896. After 60 months of antiviral treatment, almost all the patients' liver inflammation ameliorated to G1, and no patients had inflammation progression.
CONCLUSION
Besides ALT and AST, serum HBsAg and HBcrAg correlated with inflammation grade in HBeAg-positive CHB patients before NAs treatment. Moreover, the combination of HBsAg and AST exhibited excellent diagnostic ability for significant inflammation.
Topics: Humans; Hepatitis B Surface Antigens; Hepatitis B, Chronic; Hepatitis B e Antigens; Hepatitis B virus; DNA, Viral; DNA, Circular; Hepatitis B Core Antigens; Antiviral Agents; Inflammation; Liver Cirrhosis; Liver Neoplasms; Biomarkers
PubMed: 37065191
DOI: 10.3389/fcimb.2023.1083912 -
Cancers Apr 2023Aberrant gene expression is often linked to the progression of various cancers, making the targeting of oncogene transcriptional activation a potential strategy to...
Aberrant gene expression is often linked to the progression of various cancers, making the targeting of oncogene transcriptional activation a potential strategy to control tumor growth and development. The RET proto-oncogene's gain-of-function mutation is a major cause of medullary thyroid carcinoma (MTC), which is part of multiple endocrine neoplasia type 2 (MEN2) syndrome. In this study, we used a cell-based bioluminescence reporter system driven by the RET promoter to screen for small molecules that potentially suppress the RET gene transcription. We identified adefovir dipivoxil as a transcriptional inhibitor of the RET gene, which suppressed endogenous RET protein expression in MTC TT cells. Adefovir dipivoxil also interfered with STAT3 phosphorylation and showed high affinity to bind to STAT3. Additionally, it inhibited RET-dependent TT cell proliferation and increased apoptosis. These results demonstrate the potential of cell-based screening assays in identifying transcriptional inhibitors for other oncogenes.
PubMed: 37046823
DOI: 10.3390/cancers15072163 -
BioRxiv : the Preprint Server For... Mar 2023Many poxviruses are significant human and animal pathogens, including viruses that cause smallpox and mpox. Identification of inhibitors of poxvirus replication is...
Many poxviruses are significant human and animal pathogens, including viruses that cause smallpox and mpox. Identification of inhibitors of poxvirus replication is critical for drug development to manage poxvirus threats. Here we tested two compounds, nucleoside trifluridine and nucleotide adefovir dipivoxil, for antiviral activities against vaccinia virus (VACV) and mpox virus (MPXV) in physiologically relevant primary human fibroblasts. Both trifluridine and adefovir dipivoxil potently inhibited replication of VACV and MPXV (MA001 2022 isolate) in a plaque assay. Upon further characterization, they both conferred high potency in inhibiting VACV replication with half maximal effective concentrations (EC ) at low nanomolar levels in our recently developed assay based on a recombinant VACV secreted Gaussia luciferase. Our results further validated that the recombinant VACV with Gaussia luciferase secretion is a highly reliable, rapid, non-disruptive, and simple reporter tool for identification and chracterization of poxvirus inhibitors. Both compounds inhibited VACV DNA replication and downstream viral gene expression. Given that both compounds are FDA-approved drugs, and trifluridine is used to treat ocular vaccinia in medical practice due to its antiviral activity, our results suggest that it holds great promise to further test trifluridine and adefovir dipivoxil for countering poxvirus infection, including mpox.
PubMed: 36993701
DOI: 10.1101/2023.03.23.533943 -
Journal of Gastroenterology and... May 2023Hepatitis B virus (HBV) is a life-threatening infectious virus associated with the risk of liver failure and hepatocellular carcinoma (HCC). Regarding HBV treatment, the... (Review)
Review
Hepatitis B virus (HBV) is a life-threatening infectious virus associated with the risk of liver failure and hepatocellular carcinoma (HCC). Regarding HBV treatment, the recent development of nucleoside/nucleotide analogs (NUC), HBV reverse transcriptase inhibitors, enabled favorable viral control as well as improved prognosis in patients with chronic hepatitis B. However, NUC fails to clear HBV because the formation of covalently closed circular DNA or HBV surface antigen occurs upstream of the point of action of NUC. Recently, we found that acyclic nucleoside phosphonates (ANP) such as adefovir or tenofovir, but not lamivudine or entecavir, induced IFN-λ3 productions in the gastrointestinal tract and modulated lipopolysaccharide (LPS)-mediated cytokine profiles in peripheral blood mononuclear cells, such as interleukin (IL)-12p70 induction and IL-10 inhibition, which are immunologically favorable cytokine profiles for HBV elimination. Furthermore, IFN-α, in combination with ANP, showed additional and synergistic effects on IFN-λ3 and IL-12p70 production, respectively, while not affecting IL-10 levels. Mechanistic analyses of the cytokine modulation by ANP revealed that ANP blocked the mammalian target of the rapamycin (mTOR) pathway by inhibiting Akt translocation to the plasma membrane, thereby inhibiting Akt phosphorylation. As it has been reported that IFN-λ inhibits tumor growth directly or indirectly and the mTOR pathway is generally activated in most cancer cells, ANP might have potential anti-HCC effects. Our in vitro and ex vivo findings might stir the debate on whether types of NUC affect the risk of HBV-related HCC incidence.
Topics: Humans; Tenofovir; Carcinoma, Hepatocellular; Antiviral Agents; Interleukin-10; Nucleosides; Leukocytes, Mononuclear; Proto-Oncogene Proteins c-akt; Liver Neoplasms; Hepatitis B, Chronic; Hepatitis B virus; TOR Serine-Threonine Kinases; Treatment Outcome
PubMed: 36918402
DOI: 10.1111/jgh.16178 -
JHEP Reports : Innovation in Hepatology Apr 2023Pegylated interferon alpha (pegIFNα) is commonly used for the treatment of people infected with HDV. However, its mode of action in HDV-infected cells remains elusive...
BACKGROUND & AIMS
Pegylated interferon alpha (pegIFNα) is commonly used for the treatment of people infected with HDV. However, its mode of action in HDV-infected cells remains elusive and only a minority of people respond to pegIFNα therapy. Herein, we aimed to assess the responsiveness of three different cloned HDV strains to pegIFNα We used a previously cloned HDV genotype 1 strain (dubbed HDV-1a) that appeared insensitive to interferon-α , a new HDV strain (HDV-1p) we isolated from an individual achieving later sustained response to IFNα therapy, and one phylogenetically distant genotype 3 strain (HDV-3).
METHODS
PegIFNα was administered to human liver chimeric mice infected with HBV and the different HDV strains or to HBV/HDV infected human hepatocytes isolated from chimeric mice. Virological parameters and host responses were analysed by qPCR, sequencing, immunoblotting, RNA hybridisation and immunofluorescence staining.
RESULTS
PegIFNα treatment efficiently reduced HDV RNA viraemia (∼2-log) and intrahepatic HDV markers both in mice infected with HBV/HDV-1p and HBV/HDV-3. In contrast, HDV parameters remained unaffected by pegIFNα treatment both in mice (up to 9 weeks) and in isolated cells infected with HBV/HDV-1a. Notably, HBV viraemia was efficiently lowered (∼2-log) and human interferon-stimulated genes similarly induced in all three HBV/HDV-infected mouse groups receiving pegIFNα. Genome sequencing revealed highly conserved ribozyme and L-hepatitis D antigen post-translational modification sites among all three isolates.
CONCLUSIONS
Our comparative study indicates the ability of pegIFNα to lower HDV loads in stably infected human hepatocytes and the existence of complex virus-specific determinants of IFNα responsiveness.
IMPACT AND IMPLICATIONS
Understanding factors counteracting HDV infections is paramount to develop curative therapies. We compared the responsiveness of three different cloned HDV strains to pegylated interferon alpha in chronically infected mice. The different responsiveness of these HDV isolates to treatment highlights a previously underestimated heterogeneity among HDV strains.
PubMed: 36908749
DOI: 10.1016/j.jhepr.2023.100673 -
JHEP Reports : Innovation in Hepatology Apr 2023Patterns of liver HBV antigen expression have been described but not quantified at single-cell resolution. We applied quantitative techniques to liver biopsies from...
BACKGROUND & AIMS
Patterns of liver HBV antigen expression have been described but not quantified at single-cell resolution. We applied quantitative techniques to liver biopsies from individuals with chronic hepatitis B and evaluated sampling heterogeneity, effects of disease stage, and nucleos(t)ide (NUC) treatment, and correlations between liver and peripheral viral biomarkers.
METHODS
Hepatocytes positive for HBV core and HBsAg were quantified using a novel four-plex immunofluorescence assay and image analysis. Biopsies were analysed from HBeAg-positive (n = 39) and HBeAg-negative (n = 75) participants before and after NUC treatment. To evaluate sampling effects, duplicate biopsies collected at the same time point were compared. Serum or plasma samples were evaluated for levels of HBV DNA, HBsAg, hepatitis B core-related antigen (HBcrAg), and HBV RNA.
RESULTS
Diffusely distributed individual HBV core+ cells and foci of HBsAg+ cells were the most common staining patterns. Hepatocytes positive for both HBV core and HBsAg were rare. Paired biopsies revealed large local variation in HBV staining within participants, which was confirmed in a large liver resection. NUC treatment was associated with a >100-fold lower median frequency of HBV core+ cells in HBeAg-positive and HBeAg-negative participants, whereas reductions in HBsAg+ cells were not statistically significant. The frequency of HBV core+ hepatocytes was lower in HBeAg-negative participants than in HBeAg-positive participants at all time points evaluated. Total HBV+ hepatocyte burden correlated with HBcrAg, HBV DNA, and HBV RNA only in baseline HBeAg-positive samples.
CONCLUSIONS
Reductions in HBV core+ hepatocytes were associated with HBeAg-negative status and NUC treatment. Variation in HBV positivity within individual livers was extensive. Correlations between the liver and the periphery were found only between biomarkers likely indicative of cccDNA (HBV core+ and HBcrAg, HBV DNA, and RNA).
IMPACT AND IMPLICATIONS
HBV infects liver hepatocyte cells, and its genome can exist in two forms that express different sets of viral proteins: a circular genome called cccDNA that can express all viral proteins, including the HBV core and HBsAg proteins, or a linear fragment that inserts into the host genome typically to express HBsAg, but not HBV core. We used new techniques to determine the percentage of hepatocytes expressing the HBV core and HBsAg proteins in a large set of liver biopsies. We find that abundance and patterns of expression differ across patient groups and even within a single liver and that NUC treatment greatly reduces the number of core-expressing hepatocytes.
PubMed: 36908748
DOI: 10.1016/j.jhepr.2022.100664